Without limiting the scope of the invention, its background is described in connection with adhesives used in the assembly of various substrates.
Acrylic-based adhesives have been used in a wide variety of applications. For example, U.S. Pat. Nos. 4,942,201 and 4,714,730, assigned to ITW of Glenview, Ill., the assignee of the present invention, the contents of which are incorporated herein by reference, describe adhesives made with methacrylate and acrylate based adhesives, together with various other additives and ingredients, for use in the assembly of various products ranging from small component parts such as PVC pipe, to larger objects such as busses and boats.
Many available adhesives, however, have exhibited certain inadequacies in their potential application to various construction substrates. For example, many so-called “reactive” adhesives must be combined with a catalyst or other promoter in order for polymerization to take place. Oftentimes, these catalyst promoters are either mixed with the main adhesive component so that the adhesive, when applied, is ready to bond, or the various component parts are kept separate and then mixed when bonding is desired. This mixing/combining step can add significant time to the assembly process, and can oftentimes be very tedious.
In addition, many reactive adhesives cure too fast, thus not allowing the assembler adequate time to assemble the component parts before bonding, or conversely, cure too slow, thus complicating the assembly process, especially for small, intricate objects where a fast cure is desired. Similarly, while many adhesives offer easy application procedures and acceptable level of adhesion, their performance is lacking in chemical resistance and ability to withstand exposure to high temperatures.
Furthermore, many adhesives exist and are applied in liquid form. As such, because of the difficulty in transporting substrates that have liquid adhesive components already applied, assemblers are forced to apply the adhesives to the desired substrates at the location of assembly. This can of course lengthen the assembly process.
As such, there is a need for reactive adhesives that can be easily applied to a wide variety of substrates, while exhibiting high performance characteristics and a wide time window for curing before final assembly. In addition, there is a need for reactive adhesives that can be employed in ways that will improve the application of the adhesive, and that will improve the overall assembly process of substrates to which the adhesive is applied.